Yoruba is a tone language: the pitch of your voice changes what words mean. The dùndún, an hourglass-shaped drum, lets players change its pitch by squeezing the cords under their arm. Drummers reproduce the melody of sentences, and listeners who know the code can recognise proverbs, praise names or messages.
In Kuşköy, a mountain village in northern Turkey, people talk across valleys by whistling Turkish. A 2015 study showed that whistled Turkish draws on both hemispheres fairly evenly, whereas spoken Turkish relies mostly on the left. The physical form of the signal, it turns out, matters to the brain.
Speech has no gaps between words. In 1996, researchers played 8-month-old babies a continuous stream of made-up syllables for just two minutes. The infants picked out the 'words' by tracking which syllables tend to follow one another. That's probability calculation, done without a calculator or any visible effort.